The present invention relates generally to agricultural irrigation systems and, more particularly, to an improved drive tower for self-propelled irrigation systems.
Self-propelled irrigation systems are commonly used for irrigation of agricultural lands. Self-propelled irrigation systems typically comprise an elongated pipeline supported by a plurality of spaced-apart drive towers. Sprinklers spaced along the irrigation pipeline spray water as the drive towers move the irrigation pipeline over the land. In center-pivot irrigation systems, the irrigation pipeline extends radially from a center pivot, and the drive towers move in a circle about the center pivot. In lateral move irrigation systems, the drive towers move in a straight line in a direction lateral to the irrigation pipeline.
The drive towers for self-propelled irrigation systems typically comprise a generally-triangular frame with an elongated base beam extending transverse to the irrigation pipeline. In the most common designs, wheels are disposed at opposite ends of the base beam. In some designs, additional wheels may be disposed between the ends of the base beam. To prevent the drive tower from tipping over or getting stuck, the path traveled by the drive tower needs to be relatively uniform.
On some farms, the fields being irrigated may be traversed by one or more drainage ditches, irrigation ditches, streams, or water courses. The ditches may be too wide for a traditional drive tower to cross. Consequently, bridges or culverts may need to be installed at points where the drive towers cross the ditches. In some installations, hundreds of bridges may be needed for irrigation of a single field. The cost of the bridges adds significantly to the cost of the irrigation system, which is an impediment to the adoption of self-propelled irrigation systems. Also, the bridges can interfere with tractors, other equipment, and drainage.